Channelled sabot

ABSTRACT

A one piece injection molded sabot with several channels on the inner  diaer thereof. The channels run parallel to the fore and aft axis of the sabot. The ambient air rammed into the channels just after firing causes dilation of the sabot and results in rapid disengagement of the sabot and its associated projectile, thus minimizing interference with the desired trajectory of the projectile.

The invention described herein may be manufactured, used, and licensedby or for the Government for governmental purposes without the paymentto me of any royalties.

BACKGROUND OF THE INVENTION

This invention relates to the concept of saboted ammunitipn as itpertains to large and small caliber weapon systems. Both fin-stabilizedand spin-stabilized projectiles are sometimes fired from gun barrelswith a much larger bore diameter than the nominal diameter of theprojectile, to increase the muzzle velocity. The term projectile as usedherein refers to the penetrator or bullet which is intended for terminalperformance. In such weapon systems, the projectile is accelerated downthe barrel by means of a sabot which has an outside diameter equal tothe weapon's bore, to prevent the escape of gas ahead of the projectile.Just after the projectile and sabot leave the muzzle, the sabotseparates from the projectile, caused by dynamic forces acting on thesetwo components. A problem in the past with one-piece injection moldedsabots used with spin-stabilized projectiles has been interferencebetween the sabot and penetrator or bullet during sabot discard. Duringdiscard this type of sabot has a tendency to rotate slightly about itslateral axis. This usually occurs while the projectile is still withinthe confinement of the sabot, causing the projectile to yaw. This yawaffects the accuracy of the projectile and can also adversely affect theterminal performance of the projectiles, such as bullets or penetrators,at the targets.

One solution to this interference problem in the prior art was the useof a segmented sabot which comprised several pieces which fitted aroundthe penetrator or bullet in the manner of a jig-saw puzzle. Upon exitfrom the muzzle, such a segmented sabot would quickly disengage from theprojectile with minimum interference from centrigugal force, forspin-stabilized projectiles.

Segmented sabots are more difficult to manufacture and assemble andhence are more costly than one-piece sabots. Tighter tolerances arerequired and multi-operating stages during the assembling process arealso required. This is both time consumming and costly.

The channelled sabot of the present invention is a one-piece sabot whichhas the cost advantages of the conventional sabots and the performancecapability of the aforementidned segmented sabots when used withspin-stabilized projectiles.

SUMMARY OF THE INVENTION

The channelled sabot of the present invention comprises channels orslots on the inside diameter of the one-piece sabot, with the channelsrunning longitudinally at least to the base or aft end of theprojectile. These channels, with the open ends thereof facing forward,permit the ambient air to be rammed into the channels and the base oraft end of the projectile. This air pressure between the sabot andprojectile performs numerous functions. It relieves any pressuredifferentials during separation. It causes the sabot to dilate upon exitfrom the muzzle, thus relieving any frictional forces between the sabotand the penetrator/bullet, thus eliminating any yaw to thepenetrator/bullet caused by the sabot during discard. This promotes arapid discard of the sabot with minimal interference to the projectile'strajectory. The channels also provide a weakened line in the sabot'sstructure which facilitates the aforementioned dilation.

It is this an object of the invention to provide a novel channelledsabot of improved performance.

Another object is to provide a sabot with a purality of channels in itsinner diameter which run longitudinally or parallel to the bore of thegun barrel in which said sabot is used.

A further object of the invention is to facilitate the use of aone-piece injection molded sabot which rapidly disengages from itsassociated projectile immediately upon exit from a muzzle, with minimalinterference between the projectile and the sabot during disengagement.

These and other objects and advantages of the invention will becomeapparent from the following detailed description and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are side and end views, respectively, of a channelledsabot with a projectile mounted therein.

FIGS. 2A, 2B, 3A and 3B are similar views of channelled sabots withdifferent types and numbers of channels therein.

FIGS. 4 and 5 are side and end views, respectively, of a sabot and aprojectile just after firing, showing the dilation of the sabot.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

The side and front views of FIGS. 1A and 1B show the sabot andprojectile assembly prior to firing, with the nose of the projectile 7protruding from the forward end of sabot 5. The inner diameter 8 of thesabot of this embodiment is provided with four equally spacedsemi-cylindrical channels, 9, extending longitudinally along the entirelength of the inner diameter of the sabot. The variations of thisstructure illustrated in FIGS. 2A, 2B, 3A and 3B include differentnumbers of channels with different channel cross-sectional shapes,however the operating principles or mode of operation of all of theseembodiments is the same. The embodiment of FIGS. 2A and 2B includesthree equally spaced channels 11, which all have generally triangularcross sections. The embodiment of FIGS. 3A and 3B has five equallyspaced channels with generally trapezoidal cross sections. In FIGS. 2A,2B, 3A and 3B the components are indicated by the same reference numbersas are the same components in FIGS. 1A and 1B.

FIG. 4 shows a diametric cross sectional view of a channelled sabot,such as those illustrated herein, just after firing, showing how thisstructure causes dilation of the sabot with a resultant rapiddisengagement of the sabot 15 and the projectile 25. In thecross-sectional view of the sabot 15, diametrically opposed portionsthereof, 17 and 19, have dilated as indicated by the arrows 21 and 23 toopen up the inner diameter 18 of the sabot, to relieve the frictionalforces between the sabot and projectile. The arrow, v, indicates thedesired trajectory of the projectile and the arrows P_(O) indicate airdrag or pressure on the nose of the projectile. The arrows P_(I)indicate the force or pressure inside of the base of the sabot, whichpressure aids in the aforementioned dilation. The number and crosssectional shapes and areas of the channels would be selected to providethe required dilation. The design of such a channelled sabot wouldrequire a knowledge of the weapon's muzzle velocity which would be onefactor in determining the pressures P_(O) and P_(I). The inside pressureP_(I) would be utilized to cause the sabot in the area 24 to be stressedinto its plastic zone. The weakened plastic material would then easilydilate as illustrated. The channels can be considered scoring lineswhich weaken the sabot in these areas to facilitate the dilation.

FIG. 5 is a front view of the sabot and projectile of FIG. 4, whereinthe same reference characters indicate the same parts. This sabot isseen to comprise four equally spaces channels, 29, like that of FIGS. 1Aand 1B.

Currently available materials make this invention practical for smallweapons up to 30 mm in caliber. Engineering models were built and testedutilizing caliber 0.50 ammunition with the test items fired from astandard caliber 0.50 pressure barrel.

While the invention has been described in connection with illustrativeembodiments, obvious variations therein will occur to those skilled inthis art, accordingly the invention should be limited only by the scopeof the appended claims.

What is claimed is:
 1. A sabot having a body provided with a boreadapted to receive a projectile, said body having a plurality of equallyspaced channels therein, said channels running longitudinally within theinterior of the said body, parallel to the axis of said bore, saidchannels being designed to permit rapid disengagement of said sabot andsaid projectile immediately after the firing thereof.
 2. The sabot ofclaim 1 wherein the number of said channels is four and thecross-sectional shape thereof is semi-circular.
 3. The sabot of claim 1wherein the number of said channels is three and the cross-sectionalshape thereof is generally triangular.
 4. The sabot of claim 1 whereinthe number of said channels is six and the cross-sectional shape thereofis generally trapezoidal.